Regarding muting the Note® 4's stock camera shutter sound, I use and would advocate the free Play Store app "SilentCam Switch" …
https://forums.androidcentral.com/e...ails?id=com.jamworks.silentcam&token=KUyf1UXA
… a tiny 0.5 MB app that I found does the job and doesn't require root. It's an app that's really just a switch, "App is disabled" or "App is enabled", and when enabled meshes with the stock camera app to mute the shutter sound for those whose Note® 4 firmware doesn't have that provision, like mine.
The first time you run the app it will (transparently) take you to :
Settings
▸ System
▸ Security
▸ Apps with usage access
… and you just need to checkmark the app :
• SilentCam Switch ✔
… but this need be done only once like I said . . . after that you just need to make sure "App is enabled" is showing in the app for it mute the stock camera's shutter sound.
As far as this last goes, it shutter muting will remain "enabled" as long as the phone isn't rebooted. So if you don't reboot your phone for 3 days, any pictures you take in those 3 days will be taken with a silent shutter. If you reboot fairly regularly
and tend to take pictures frequently
and want the shutter to be silent all the time, you'll need to enable it after every reboot, which basically just entails 3 taps : tap to launch the app, tap to change "disabled" to "enabled", tap to back out of the app. At that point you're geared for silent picture taking until the next reboot of your device. So while it hardly takes 5 seconds to enable the app, I couldn't help wish for an "Automatically enable with every boot" setting.
This last is the only drawback, and is why I gave the app 4 stars instead of 5 in my rating, but on the plus side it works perfectly with the Note® 4, even if your device isn't rooted (mine is, but the app doesn't require it) and works without you having to mute the device or alter your sound settings in any way.