I just noticed last night that comments are monetized now.

If you go to your stories tab, then to your responses tab, then over any response click the 3 dots, you can now click edit settings, it then opens a settings page for that one comment, where you can add topic tags and check the add to partner program box.

You have to turn it on one at a time for each comment individually, and..

…it only shows up for comments that you set to display on your profile.

It does not show up on comments, where you did NOT check the "Also publish to my profile" tab.

I only just noticed it last night, and don't remember seeing it before, so I don't know if I just missed it before or if it is a new feature.