import panel as pn

numbers = [1, 2, 3, 4, 5]

def square_numbers():
    squared = [num ** 2 for num in numbers]
    return squared

pn.extension()

button = pn.widgets.Button(name='Square Numbers', button_type='primary')
output = pn.widgets.StaticText()

def button_click(event):
    output.value = str(square_numbers())

button.on_click(button_click)

app = pn.Column(button, output)
app.servable()