Online check the Contact (email) Form for spam/robots attacks

I have a form with several fields and a captcha protection. However, the mailbox was spammed anyway via the form (automated?)submission (because subjects are advertising, and seems to be automated).

I did some improvements on it. It's online, but I don't know if my improvements works or not. I should wait an unknown amount of time to (maybe) be spammed again (or not).

Wondering if there are some (online) tools to test a online form for the spam/robots attacks ?

Something like I submit the "www.mysite.com/contactme" and it tells if the form is open or not to automated emails to be sent?