To hide photos from gallery app you have to move them to secure folder. And as far as I know there is no specific option to turn off camera sound. You have to mute system sounds.
We acknowledge your query kindly perform the following steps to turn off the camera sound while taking pictures.
1- Turn off the Shutter sound: Navigate to and open the Camera app, and then tap the Settings icon. Swipe and tap the switch next to the Shutter sound to disable it.
2-Use the Volume Down key. If you do not have the Shutter sound option, you can turn down your phone's System volume. To do this, press the Volume down key while on your phone's Home screen, and then tap the three dots at the top of the slider to open more volume settings. Use the slider to turn down the System volume. You will not be able to hear the shutter if the System volume is all the way down.
