How to implement feedback with ReCaptcha on an HTML site?

Question

HTML

Good evening! I cooked up a simple site with several pages without an engine, using pure HTML and CSS. On one of the pages I want to insert a feedback form with the fields "Name", "Phone / email" and "Message", and below the Google captcha "I'm not a robot", and for the sake of beauty, do all this with Ajax so that the page does not reload. I stylized the form itself, it remains to make it work. I don't know PHP and Ajax at all, I can only tweak something in someone's code. Tell me, where can I find ready-made projects similar to what I'm looking for? Everywhere I see either without captcha, or with Google without Ajax, or with a question like "how much is 2 + 4". Thanks in advance.