Yes you can.
Find a surface that you trust to to be level
Open the compass/spirit level app and place phone on it
Tap the screen while phone is placed on the surface - this will recalibrate the accelerometer reading on your iphone6 implicitly
taking into account the camera bump as well.
Go measure the things you want to measure :)
There is a catch to this,...
In troubleshooting this, I learned a few important things:
While there is no way to manually force a recalibration of the compass aside from toggling location services on and off, generally the compass attempts to recalibrate itself when an app requests it if it has not been in use.
The 'blue cone' in maps seems to be the best way to easily tell how ...
This is determined by satellites in the horizon mapping out where your phone is (according to multiple posts on Stack Overflow, including https://stackoverflow.com/questions/13329714/how-does-my-iphone-get-its-altitude). Note that the accuracy from this method is not usually precise, but it is a rough estimate of your elevation.
I don't think anyone here will be able to give you a definitive answer to this, unless of course they've tried to do something similar.
Apple only provides very basic specs in terms of its sensors (e.g. accelerometer, gyro, proximity, compass, barometer, etc) and doesn't go into their individual specifications.
However, considering that anyone can build a ...
There's currently no way to get data from the iPhone's Compass app to your Apple Watch, and no complication option available. There is no API on watchOS for compass heading and you would need to have your iPhone / iPad out and pointing in a specific location for the watch to match the iOS device.
I suppose you could mount the phone to a stand inside a ship ...
I found an answer from another site that worked instantly with my iPhone SE:
Hold phone flat, face up in front of you (on the palm of your hand)
Move the phone in a figure of eight motion (by tilting your wrist)
While making this repetitive movement, the compass will reorient itself.