Clients sometimes ask why captcha is not working correctly for them. Because of how the plugin works, captcha for Gravity Forms will not work and is not needed.
The plugin replaces the submit button via Javascript after the page loads and the button becomes a div element with an on click event; not an actual form submit button.
Bots that search for submit buttons or any buttons will not find a button on the form. In addition, we also append a hidden "Honey Pot" field to the form and validate against it when a form is submitted.
While nothing is 100% effective, these two methods combined should prevent most spam form submissions.