This app was mentioned in 1 comment, with an average of 3.00 upvotes
You can install a separate camera app without the shutter sound. UVA Silent Camera is handy.
At work, I sometimes have to get the serial off the backs of computers that are under desks while people are sitting at nearby desks. It weirds people out if the guy next to you puts his phone under the desk and you start hearing the shutter sound.