In the Samsung Galaxy Note 4, you can configure the Home button to be used as answering calls button and the power button to be used as ending calls. Below is a video that shows you how you can enable the functions in your Samsung Galaxy Note 4 settings.
Video ScreenshotsGo to "Settings".
Go to "Accessibility".
Go to "Answering and ending calls".
Check the checkboxes for "Pressing the Home Key" and "Pressing the Power Key".