Apple Insider reviewed the Fibaro Motion HomeKit Sensor
A quote from the article:
Motion sensors certainly aren't the flashiest of HomeKit accessories, but they can add a lot of options to HomeKit installations. Fibaro makes the best out there with not just motion detection, but two other sensors packed into its slightly quirky body.Fibaro Motion HomeKit Sensor Review
A big difference exists between a connected home and a smart home. Sensors and carefully crafted automation rules can help make your home make changes itself instead of always relying on interaction from you.
There are a ton of perks to having a motion sensor in your HomeKit-equipped home. Motion sensors can do everything from alert you if there is someone in a restricted area, to triggering lights on and off as you enter or leave rooms, or enabling a nightlight in hallways.