As per help documentation provided by adobe How eVars work in Adobe Analytics,Success events and eVars are frequently defined in different image requests. is it possible to capture only success event with out associating it with any evar?
Reason: we would like to ask this because we are running out of evars and would like to capture user interaction through success events only and in reports we still want to get count of interaction user has performed on the website.
For Ex: On our website, we have contact-us form where in user submits the request for contact us, here we would like to capture how many users have submitted the contact-us form. Count is enough in the reports which will give us the exact thing we want.
here event = ContactUssubmitted
We also know in workspace, if we use ContactUssubmitted as dimension, it will show All Visits Metirc by default and it gives the count as below
and if we use ContactUssubmitted as metirc, by default it will use day as dimension as below
To directly answer your question, you can absolutely set an event without having to use an eVar.
However, the reporting in your post should be possible through segmentation/a calculate metric without using an event or an eVar at all if you've got your implementation right. Whether you are capturing the 'contactussubmitted' as a page view or as a custom link tracking call you should be passing an identifier that you could use to segment on to create this ('page' [name] on a page view, or 'custom link' for link tracking)
Also, how many eVars have you got? Most of the latest contracts with Adobe give you 200; if you've only still got 100 it might be worth speaking to Adobe about moving to one of their latest contracts.