Captcha on post

Hi and goodafternoon digitalpoint community members. I was wondering if anyone knows how to get a captcha on a forum posting like the way it is here on digitallpoint. I have searched for a plugin for vbulletin how ever was not able to find out. Kindly inform me if anyone has found the plugin.

 

In the usergroup permissions, turn on "Require Human Verified Actions"

 

Thanks worked like a charm