When the accessory is near you, it is automatically marked as found, and Find My Device notifies you. To mark an accessory as lost, follow these steps: Each device has a unique IMEI number.
There are two ways to find the IMEI number on your iPhone. 1. Start the Settings app. 2. Tap "General," and then tap "About." 3. Scroll to the bottom of the page, and you'll see the IMEI number.