This app is designed to be used as motion sensor (detector) or/and burglar alarm. It has a very simple interface, has one button to active alarm and one slider to set sensitivity of alarm.
It has application background support which lets the app to be active and running if it is at background or screen-lock activated unless you deactivate the app manually. You can use your iDevice as very accurate motion sensor. It has loud alarm sound which will make you aware of if somebody moves your device.