The keyboard clicks are turned off in the image below. You will know that it is turned off when the button is in the left position, and there is no green shading around the button.
Fortunately you are not stuck with this setting, and you can turn off the keyboard clicks on your iPhone 6 in iOS 9. This can quickly become annoying, however, to both you and people that are nearby. One of the noises that it will make is a series of feedback clicks that are played whenever you type a letter, number, or character on your keyboard. Your iPhone will make a lot of sounds and vibrate in a lot of situations when your settings are still at their default options.