The return on investment (ROI) of your website is difficult to measure without direct website selling. Without those online sales, it's difficult to determine how effective your website, and overall online marketing strategy is. One way to measure your ROI is to have a web form to request more information.
Online forms are limited only by your imagination and can have fields to request any tidbit of information you desire. Some jewelers will ask for a birthday and anniversary; some will ask for your favorite precious metal or gemstone; then of course you have the basic contact form that only asks for a name, email and to fill out a comments box.
It all depends on your needs but once the person fills out the form you might reward them with more information, or a downloadable newsletter, or perhaps access into a protected area of your website.
Those web forms are very beneficial, many of the websites we manage will receive at least legitimate request per week through them. Make sure you monitor all the requests that come from your contact form.
As Google crawls the web they will try to fill out your form to see what's past it. In other words, Google's automated system will attempt to randomly enter information into a form in order to reach whatever information you have deeper in your website.
For many years our staff was baffled on how Google would sometimes find protected information that was behind a web form. But then in one of Google's YouTube videos they casually mentioned that they try to auto-fill in your forms.
So how do we prevent this? One way is to include a CAPTCHA protection of some type. The other way is to put this meta tag at the top of your HTML code:
<meta name="robots" content="noindex,nofollow" />
That line of HTML code will tell Google to stop and do nothing when they get to your form page. Actually you can use that same line of HTML code on any webpage you don't want Google to remember when they find it.