Getting other details is easy, but there doesn't seem to be any API accessible way to get a list of users (or even approximate users) for the audience. You can add them, and delete them (?!) but not enumerate all the users in the list.
Is that truly the case, or am I missing something?
According to the documentation here: https://developers.facebook.com/docs/reference/ads-api/custom-audience-targeting/ you should be able to see an approximate count.
There is no way to get the users back from the custom audience list by design.
For the audiences you never upload raw contact data. You always have to hash it via SHA256 and send the feed to Facebook that way. Since you have not provided the actual contact information like email, phone number facebook won't give those back to you it would be an information breach in a way.
If what you are asking is whether you can retrieve back the hashes that you have sent, I have not been able to find a way it on the API so I assume they think that you already have that list since you uploaded it in the first place.
https://developers.facebook.com/docs/marketing-api/audiences-api/
来源：https://stackoverflow.com/questions/16426776/is-there-any-way-to-get-a-list-of-users-for-a-custom-audience