A Different Kind Of Captcha
I've been looking all over for a decent looking alternative to recaptcha, only because recaptcha cannot be used more than once per page. This poses a problem on the ad page because a person would ideally want to use recaptcha for the comments - as well as the contact form.
-reCAPTCHA" seems to work fine for version 3.02 in the comments & registration areas, so it is easiest to stick with that. The plugin doesn't show that it works for WP
2.92, but it appears to handle it without a problem.
I spent a long time looking, and then I remembered something I saw a few months ago. It's a drag and drop captcha that looks really great. WDB Fancy Captcha. It's a different way of thinking about captcha.
(The site takes a little bit to load, but give it time and you will see what I'm talking about.)
I downloaded it and it doesn't look like it would be hard to integrate, but I know little more than nothing about forms. This plugin uses its own ID and action for the form that it would be added to. I don't know how to do this without breaking everything.
There appears to be very little coding involved if it could be made to work with the contact form. This should be much, much easier than integrating reCaptcha to the contact form. If it can be done, it would then be possible to have nice looking captchas for both the comments and the contact form. A nice addon to ClassiPress.