Um... why don't you just keep the window up if you don't want people reaching inside?
Although, what you describe sounds like an old way to catch raccoons. Take a jar and circle the opening with nails slanted inward. Then put some goodies inside. The raccoon can get in, but can't get out without tearing off his hand, so he's caught red handed... literally.
I always thought, however, that the whole point of alarm systems and the like is deterrence, not apprehension.
Although, what you describe sounds like an old way to catch raccoons. Take a jar and circle the opening with nails slanted inward. Then put some goodies inside. The raccoon can get in, but can't get out without tearing off his hand, so he's caught red handed... literally.
I always thought, however, that the whole point of alarm systems and the like is deterrence, not apprehension.