Drupal 8: Add Captcha to Post Comments
It sounds like a very common thing to me. You post some content, you want others to comment, comments invite bots, you want a Captcha question. In D8 by default this is turned off. Unfortunately in Drupal 8 it is also not easy to find this setting.
Here is the solution, from mmerrill219:
To add Captcha to Drupal 8 Comments one must:
– Goto “admin/config/people/captcha/captcha-points”
– Click ” + Add Captcha Point” button at top of page
– Use “comment_comment_form” as Form ID