Here is another sensor that detects motion in your home and alerts you on your phone. The BroadLink Smart Motion Sensor sends you push notifications when unexpected movement is detected in your home when you are not around. It has up to 29.5ft range and 120-degree coverage.
This motion sensor combines with your other connected devices to make your home smarter. For instance, it can turn your lights off or shut off your heater when nobody is detected in a room for a few minutes. It works with IFTTT and Alexa.