How can I require a captcha to load a page?

I would like a simple PHP captcha script that would require the user so solve a captcha to load the website page. Preferably a captcha that doesn't need a third party such as reCAPTCHA, all done locally.

EDIT: Ended up making a text box to enter the link you would like to protect and it would automatically generate a captcha protected link, and a deletion link to delete the protected link.

source https://stackoverflow.com/questions/73602263/how-can-i-require-a-captcha-to-load-a-page