An apparatus comprising a housing , the apparatus being adapted to be inserted into a cavity of an outdoor device, - the apparatus comprising a light sensor for detecting ambient light; - the apparatus further comprising at least one light source (1062a, ... 1062h); characterized in that - the at least one light source (1062a, ... 1062h) is arranged in the housing , - the housing comprising at least one housing through-hole (1041a, ... 1041h, 1051), the housing through-hole (1041a, ... 1041h, 1051) being configured for forwarding light generated by means of the at least one light source (1062a, ... 1062h) out of the housing ; - the light sensor being arranged in the housing and the at least one housing through-hole (1041a, ... 1041h, 1051) being further configured for forwarding ambient light to the light sensor ; - each light source (1062a, ... 1062h) being arranged at a distance from a housing inner side of the housing , the generated light being adapted to be coupled into the light sensor due to the distance ; - the apparatus comprising a control unit , the control unit comprising a timing controller, the timing controller cyclically causing the control unit to deactivate each light source (1062a-h) in a time interval of an actuation in which the ambient light is to be detected by means of the light sensor by the control unit ; - the control unit being configured to ignore a light sensor output signal of the light sensor at times in which the light sources are activated and to evaluate the light sensor output signal at times in which the light sources are deactivated; and - the control unit being further configured to generate an alarm signal if the detected ambient light exceeds a predefined threshold value. - the apparatus comprising a light sensor for detecting ambient light; - the apparatus further comprising at least one light source (1062a, ... 1062h); characterized in that - the at least one light source (1062a, ... 1062h) is arranged in the housing , - the housing comprising at least one housing through-hole (1041a, ... 1041h, 1051), the housing through-hole (1041a, ... 1041h, 1051) being configured for forwarding light generated by means of the at least one light source (1062a, ... 1062h) out of the housing ; - the light sensor being arranged in the housing and the at least one housing through-hole (1041a, ... 1041h, 1051) being further configured for forwarding ambient light to the light sensor ; - each light source (1062a, ... 1062h) being arranged at a distance from a housing inner side of the housing , the generated light being adapted to be coupled into the light sensor due to the distance ; - the apparatus comprising a control unit , the control unit comprising a timing controller, the timing controller cyclically causing the control unit to deactivate each light source (1062a-h) in a time interval of an actuation in which the ambient light is to be detected by means of the light sensor by the control unit ; - the control unit being configured to ignore a light sensor output signal of the light sensor at times in which the light sources are activated and to evaluate the light sensor output signal at times in which the light sources are deactivated; and - the control unit being further configured to generate an alarm signal if the detected ambient light exceeds a predefined threshold value. <EOS>