Yes, you can make your own CAPTCHA plugin, see the docs here.
There are also a few different CAPTCHA plugins available here.
Welcome to the Q&A site for Question2Answer.
If you have a question about Q2A, please ask in English.
To report a bug, please create a new issue on Github or ask a question here with the bug tag.
If you just want to try Q2A, please use the demo site.
July 15, 2020: Q2A 1.8.5 released!