How to attach a captcha to a button on a website?

Question

Google

Hello!
Interested - how to attach a captcha to a button on the site? That is, there is a button "Go to the site". If a person clicks on it, then he will not be able to go to the site, if a person passed the captcha, then, accordingly, he could get to the site.
Captcha from Google

PS: PLEASE HELP

Answer 1

In a nutshell can not describe, here is the instruction . Captcha is needed for registration or for frequent user activity, and not for opening external links on the site.