[PLUJ]

You can buy a motion detector and when people walk onto your driveway it goes off. I have one in my garage (I have an open garage). At 4am in the morning I busted a theif and told him to fuck off and haven't had any problems now. Sometimes though squirrels or animals go in my garage and the alarm goes off. If you do buy one, spend more money and buy a good one, my sensors reaction time is a bit slow.