You can enable it from the Plugins option. Q2A is providing this plugin OOTB now with name as reCaptcha. You have to create Key and Secret for the same.
To create Key and Secret :- https://www.google.com/recaptcha/admin
" You can enable it from the Plugins options. Q2A is provide plugin OOTB this now with name is reCaptcha . You must create Key and Secret for same."
I AGREE WITH THIS COMMENT AGREEMENT
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.
Dec 1, 2018: Q2A 1.8.1 released!