How to grab content from between two double brackets

How to grab content from between two double brackets

I have RegEx that I believe should work, but isn't.
I would like to grab 'test' out of [[test]].
I have tried:
\[\[(\w+)\]\]
\[\[([A-z]*?)\]\]
\[\[(.*?)\]\]
All of which just grab the whole thing. Meaning, it grabs [[test]],
instead of just the content. I am unsure how to get a regex that will grab
JUST 'test' and not the brackets.