Set the Car Clicker Key by your bed at night: Problems: Set off car alarm.

http://www.ijreview.com/2015/11/462318-everyone-knows-this-is-used-to-unlock-your-car-but-theres-another-use/?utm_source=email&utm_campaign=ijwrap&utm_medium=owned

If you hear weird noises or feel that someone is trying to break into your house, set off the car alarm with your car, key clicker.  That will sound the horn and people will look out and possibly call for help.  Those creating mischief will often leave when they hear the horn as well.

I just thought this was a good idea.