Hi Daniel,
There is no OOTB captcha component available in AEM Forms as of today. There is a captcha component available OOTB as part of AEM Foundation component as seen here [1] in CRX/DE.
You can anytime create a custom component in AEM forms for your usecase.
Thanks,
Rishi
[1] /libs/foundation/components/form/captcha/captcha.jsp