This plugin stops bad bots from attacking your forms using hCaptcha or simple maths questions
hCaptcha is a drop-in replacement for Google's reCAPTCHA, but with the added benefit of getting paid for challenges completed.
"Private. Secure. Faster. And we pay you to use it."
Please note, you will need a free hCaptcha account for this plugin to work in hCaptcha mode, but the simple maths questions mode works locally with no account required.