How to carry data over from website contact form into ZohoCRM to show that lead source is from Facebook?

How to carry data over from website contact form into ZohoCRM to show that lead source is from Facebook?

When a contact form is made by a prospect, it will automatically show on the CRM as "Web Enquiry". But what if that lead actually came from a Facebook Ad that we are running. How can we automatically carry data from Facebook to website then to ZohoCRM to show that the lead source is from Facebook?

Thanks