Can a stamped, unused and revoked H1b be used for a cap exempt petition?

I got my H1b stamped in 2014 but due to project issues couldn’t travel on it.

I left the company in 2016 to do a MS on a F1 visa and the company got my H1b revoked a few months after that.

Now I am on post-completion OPT.

Can a new employer file a cap-exempt petition on the basis of previous approval?
I have the i797 and all the paperwork.

Legally, you can apply for cap-exempt H1B using your unused H1B.

But, off late, we have seen that USCIS issues an RFE to prove your H1B status before they can approve the cap-exempt H1B transfer.

So, just talk to your employer and if they are interested in going ahead with your case.

How does one prove the H1b status beyond the previous i797 and the stamped visa ?

I do not understand your question.

How can you be in status if you do not have an approved i797?

I meant in response to the RFE , how do we prove H1b status ? The new petition will mention the details of the previous approval anyhows. What additional proof can be given ?

Your attorney will guide you as to what documents are required based on if you get RFE.