scripting to process action according to hidden field

I installed Contact 7 Form Modules and it works fine. I added a couple hidden fields to the form; looking at the page source they are there.

The next task is to have the form process according to the hidden fields (or even something in the subject 9your-subject].

For instance, if hidden field xyz has been filled in, then I know it’s a bot, a spammer, so I either politely exit or perhaps collect the IP address and pass it along to honeypot. So, some action. Simple action:

code<?php
if ( $my_hidden_field ) { $spambot = true; exit; }
if ( $email-subject == “whatever” ) { $spambot = true; exit; }
?>
code

Where would I set this up (what file to edit), how do I use the wordpress variables?

https://www.ads-software.com/plugins/contact-form-7-modules/