AirTag

Apple has some suggestions under the heading Get information about or disable an AirTag, Find My network accessory, or set of AirPods in the support document What to do if you get an alert that an AirTag, Find My network accessory, or set of AirPods is with you - Apple Support

If you have found an unknown AirTag, you can follow these steps to see information about it, or to disable it: 

1. If you have found an AirTag, hold the top of your iPhone or NFC-capable smartphone near the white side of the AirTag until a notification appears.
2. Tap the notification. This opens a website that provides information about the AirTag, including its serial number and the last four digits of the phone number of the person who registered it. This can help you identify the owner, if you know them. You might want to take a screenshot to make sure that you can document the information.
3. If the owner marked the AirTag as lost, you might see a message with information about how to contact the owner.

To learn more about a set of AirPods, or Find My network accessory that’s been separated from its owner, scroll to the bottom of the Items tab, then tap Identify Found Item.

If you need to see a list of all AirTag and Find My Network accessories about which you have been notified, launch the Find My app on your iPhone, iPad, or iPod touch. Tap Items. Scroll to the bottom and tap Items Detected With You. Items that have recently triggered an unwanted tracking alert will be listed. If the option to play a sound isn't available, the item might not be with you anymore, might be near its owner, or if it was with you overnight, its identifier might have changed.

To disable the AirTag, AirPods, or Find My network accessory and stop it from sharing its location, tap Instructions to Disable and follow the onscreen steps. After the AirTag, AirPods, or Find My network accessory is disabled, the owner can no longer get updates on its current location. You will also no longer receive any unwanted tracking alerts for this item.

If you feel your safety is at risk, contact your local law enforcement, who can work with Apple to request information related to the item. You might need to provide the AirTag, AirPods, Find My network accessory, and the device's serial number.