Hi Brian,
I am afraid that IP display option was not added for Form Builder.
Even in Contact Addon EU users has a problem with it, becuase of GDPR law "hypothetical" issues.
But you can copy & add code used in Contact addon (components/com_sppagebuilder/addons/ajax_contact/site.php, line 375 and 404), add it inside Form Builder (site.php) and then override that addon inside component or template folder to have it. It should be quite easy php customization, but beyond our support.
Yes, I realize that sometimes it is useful to know the IP of the spammer to block him.