On Android devices, you can find your GAID(Advertising ID) in your device settings. Navigate to Settings, click Google, and then Ads:
You can also find the GAID programmatically. Learn how to get a user-resettable GAID.
On Android phones, you can find the IMEI number in the *Settings* menu. It can usually be found in one of the following locations, depending on the brand and Android version you are running.
From there, write down the number or take a screenshot. The screenshots above were derived from an LG V40 ThinQ running Android 10.
You also can find IMEI programmatically.
OAID is needed for android 10 and above
At this moment, you only could check OAID programmatically, import the mobile security sdk, then check the OAID with the following code.
Currently, Apple does not surface the IDFA by default on iOS devices. However, it can be retrieved using third-party apps("MyIDFA"). Check the App Store for apps that can retrieve your advertising ID, or find your IDFA programmatically.