After uploading the code the Piezo will start making short beeps. On bright light the Piezo will only beep and on dark light it will be short. Some ideas for this experiment: Alarm for Lights in the ...

Piezo Trigger Switch circuit described here is a microcontroller-compatible shock/impact sensor switch module works on 5VDC supply. The whole circuit can be assembled on a 5×7 cm common circuit board.