You can add any portion of NC to your HUDs. I think some locked HUDs would be impossible to add things to but that doesn't seem to be what you're asking. If you are asking about that main NC icon with the popup you just have to add the NC.PlayerOverview stat to your table panel and it should appear. Any other portion of the HUD can also be added. There is a very well written article here
https://www.pokertracker.com/guides/PT4 ... or-a-popup but if you are curious about anything in particular please feel free to ask here and I'll try and clarify.