Collect user data via DFU

Hello, Customer brought me a iPhone 6 with a password , the client is only interested in his photos, But only in DFU mode. Coleague said that could extract data from it in this state, at first I didn’t believe, but he actually did a few hours..He was removed from the data connector of the data only. My question is: what cable / adapter / whatever it is used to retrieve user data? Can someone enlighten me about this? W