How to shoot a rock-solid hot pot fishing mobile phone?

According to the inquiry of iQiyi, the shooting method is as follows:

The scene of hot pot fishing for mobile phone in the movie "Rock Solid" was shot in a closed studio, not a real hot pot. During the filming, the director asked the actors to stand in a pot of hot pot, holding mobile phones in their hands and pretending to catch them. Through post-production, the mobile phone is turned into a real mobile phone, showing the effect of fishing mobile phone.