My H1 has been picked by the previous employer?

My H1 has been picked by the previous employer? I left the company now , How do i get the details without asking the employer?

I am ok to transfer that to my new company, they asked me to bear the cost of the transfer

You cannot get such details, unless you have the H1B receipt number. You may request it via FOIA, but not sure, how far you can get without any info.

You should not pay for H1B, it is considered illegal. Check H1B Fee - Who Pays for What