[regex] Regex find word in the string

In general terms I want to find in the string some substring but only if it is contained there.

I had expression :

^.*(\bpass\b)?.*$

And test string:

high pass h3 

When I test the string via expression I see that whole string is found (but group "pass" not):

match : true
groups count : 1  
group : high pass h3 

But that I needed, is that match has 2 groups : 1: high pass h3 2: pass

And when I test, for example, the string - high h3, I still had 1 group found - high h3

How can I do this?