This simple app lets you copy your device advertising id .

with this app you can get Google Advertising ID (AAID) for Android devices
Inventory bid requests from Android devices pass the AAID,
which provides the same type of device-specific, unique,
resettable ID for advertising as the IDFA or uuid .

what is ad id
An advertising ID is a unique user ID assigned to a mobile device, or operating environment, to help advertising services personalizing their offers. It can be sent to advertisers and other third parties which can use this unique ID to track the user's movements, habits, and usages of applications.