Extract data between Round Bracket

I have an pdf extract field that extracts a string for example “Mr AB Sample (123456789)”. I only requre the portion of the data contained withtin the round brackets (excluding the brackets themselves). I believe this can be accomplished with a post function script.

Could anyone let me know how this can be achieved?

In the post function, use this expression:

match(/\((.*)\)/)[1]

Worked like a charm, thanks Phil