Is he around an idiom?

"Is he around?" is not an idiom. It's a straightforward question asking about someone's presence.

However, there are several idioms that are similar in meaning:

* Is he about? - This is a more informal way of asking if someone is around.

* Is he in the vicinity? - This is a more formal way of asking if someone is nearby.

* Is he hanging around? - This implies that the person is in the area and possibly idle.

The best idiom to use depends on the context of the conversation.