Do I need to hire miners if I don't know how to mine? I am studying Blockchain technology and found out that miners are the ones that provide Proof of Work and verify the transactions on the Blockchain. If I were to build an app that would involve the release of verified documents, would the verifying authorities need to have hired miners to be able to provide verification or are verification and mining 2 separate processes?
Mining and verification are different. Miners verify blocks, and verify what they're mining on before they mine it. Users also verify blocks, but do not mine them.

Mining and verification solve different problems. Verification makes sure that a transaction doesn't spend more than a person has. In this context, verification doesn't mean looking at official documents. Mining is used to determine what order two transactions happened in.