MoCa is a camera app that can work as a security camera. This app automatically starts recording the video of your device's camera when it detects movement. You can go to the settings to customize the recording length you want.

The app is compatible with Android devices. It can work even if the screen is off. The background recording mode also is ideal for saving battery.

This is very simple and easy to use. It also has a widget so that you can easily access the controls from the home screen of your phone.