Wireless Nest Secure Alarm System Door Detect Sensor Remote Access Home Security Additional Nest detect sensor for the Nest secure alarm system. Keep track of more doors, rooms and Windows. 1-sensor can detect 2-things: when a door or window opens and when there’s motion in a room. Stick it on a door. You’ll know when it opens and closes and if there’s motion in the room. Stick it on a window. You’ll know when it opens and closes. Stick it on a wall. You’ll know when there’s motion in a room. Open quietly. When the house is armed, just press the button to open a door. The alarm stays quiet and the house stays armed.