In a collaborative effort, Apple and Google have developed an industry-standard detection feature called "Detecting Unwanted Location Trackers" (DULT) for Bluetooth trackers. This standard allows users on iOS and Android devices to be alerted if an unknown Bluetooth tracker is monitoring their location.
That is how it works. Unwanted tracking notifications only trigger if separated from the owner for some time. It’s possible the paired iPhone was drained or had Bluetooth disabled which would cause the tracker to think it’s separated.
iPhones And Androids Can Now Warn You of 'Secret Trackers' ( www.ibtimes.co.uk )
In a collaborative effort, Apple and Google have developed an industry-standard detection feature called "Detecting Unwanted Location Trackers" (DULT) for Bluetooth trackers. This standard allows users on iOS and Android devices to be alerted if an unknown Bluetooth tracker is monitoring their location.