A portable device (101, 201, 400, 700), comprising: a housing; a memory; a light emitting unit positioned on at least one surface of the housing and configured to radiate light; a light splitter configured to split the light into at least one wavelength band; a light receiving unit positioned on the at least one surface of the housing and configured to receive at least some of the light; a display; and a processor electrically connected to at least one of the light emitting unit, the light splitter, the light receiving unit, and the display, wherein the processor is configured to: control the light emitting unit to radiate light to a skin of a user, control the light splitter to split the light, control the light receiving unit to obtain a first spectrum of a first wavelength band based on at least some light scattered and returned among the light radiated to the skin, determine a first degree of hydration associated with the entire skin based on the obtained first spectrum, control the light receiving unit to obtain a second spectrum of a second wavelength band based on at least some light scattered and returned among the light radiated to the skin, determine a second degree of hydration associated with a surface of the skin based on the obtained second spectrum, determine a third degree of hydration associated with a dermis of the skin by subtracting the second degree of hydration from the first degree of hydration, collect biometric data including the third degree of hydration, and control the display to display a personalized user interface to the user based on the collected biometric data. a housing; a memory; a light emitting unit positioned on at least one surface of the housing and configured to radiate light; a light splitter configured to split the light into at least one wavelength band; a light receiving unit positioned on the at least one surface of the housing and configured to receive at least some of the light; a display; and a processor electrically connected to at least one of the light emitting unit, the light splitter, the light receiving unit, and the display, wherein the processor is configured to: control the light emitting unit to radiate light to a skin of a user, control the light splitter to split the light, control the light receiving unit to obtain a first spectrum of a first wavelength band based on at least some light scattered and returned among the light radiated to the skin, determine a first degree of hydration associated with the entire skin based on the obtained first spectrum, control the light receiving unit to obtain a second spectrum of a second wavelength band based on at least some light scattered and returned among the light radiated to the skin, determine a second degree of hydration associated with a surface of the skin based on the obtained second spectrum, determine a third degree of hydration associated with a dermis of the skin by subtracting the second degree of hydration from the first degree of hydration, collect biometric data including the third degree of hydration, and control the display to display a personalized user interface to the user based on the collected biometric data. control the light emitting unit to radiate light to a skin of a user, control the light splitter to split the light, control the light receiving unit to obtain a first spectrum of a first wavelength band based on at least some light scattered and returned among the light radiated to the skin, determine a first degree of hydration associated with the entire skin based on the obtained first spectrum, control the light receiving unit to obtain a second spectrum of a second wavelength band based on at least some light scattered and returned among the light radiated to the skin, determine a second degree of hydration associated with a surface of the skin based on the obtained second spectrum, determine a third degree of hydration associated with a dermis of the skin by subtracting the second degree of hydration from the first degree of hydration, collect biometric data including the third degree of hydration, and control the display to display a personalized user interface to the user based on the collected biometric data.