Hi,
Unfortunately, there is no captcha that could provide 100% spam protection. Real people (and spammers) can get through captcha easily. Here is a list with simple recommendations to stop spam on your WordPress website:
1) Make sure that the Captcha plugin is installed, activated, updated to the latest version and integrated with your form(-s).
2) Enable all captcha protection complexity. Go to the plugin settings page and enable such options as Plus, Minus, Multiplication; enable Numbers and Words.
3) Try to submit form(-s) with captcha (use wrong answer to make sure that Captcha is working correctly).
4) Install and activate Limit Attempts plugin to get additional anti-spam protection and low-down bots registration rate. Learn more – https://www.ads-software.com/plugins/limit-attempts/
Sincerely,
BestWebSoft Support Team