From: Recalibrate Unresponsive Home Button
Open any general app like, Weather that comes pre-installed on your iPhone 6/6 Plus.
At the same time, press and hold the Power (sleep/wake) button until the “slide to power off” slider appears.
Release the power button and then press and hold the home button until the, “slide to power off” slider vanishes.
The application you’ve chosen closes, and you’ll now have a more responsive [iPhone 6/6 Plus] home button.