This device runs off 2 AA batteries hence the 2 1.5VDC power sources.
The SPST switch simulates a connector/connection that should be broken as someone tries to steal your laptop from your bag, as example.
The relay with an activation voltage of 3VDC is based on a relay I found online.
As soon as someone pulls out your item which causes the connection to be broken, the relay no longer gets powered and the upper circuit is being powered.
The LED is just a placeholder and should be replaced by some more circuitry, like an alarm.
I'm new to electronics and this is one of the first projects I'm planning to build, I highly appreciate comments, ratings and advices!