Hi Geeta
sorry for my ignorance but what is a BRP? My spousal visa is inside of my passport. I don't have anything else as I am on my 1st issuance.
In your case, you only send your passport.
You have to send both your passport and visa. If the visa was issued outside the UK, it will be a sticker in your passport. If it was issued inside the UK, it is a separate Biometrics Residence Card (BRP) in addition to your passport.
So, if your visa is in your passport, you only send your passport. If you have a BRP visa, you send that as well as your passport.