The MS100 Smart Motion Sensor from TP-Link works in conjunction with the SR20 router (available separately) to alert you of motion activity in your space. The sensor connects via Zigbee protocol to the SR20 router, which works as a hub. Two included AA batteries provide up to 2 years of battery life.
The free Kasa app for iOS and Android devices offers remote viewing and management of your devices. Additionally, you'll be able to receive notifications from anywhere.