A new app called allows iPhone 6s users to use the device's 3D Touch input for providing relative weight comparisons between objects. Don't throw out your digital scales, because this app doesn't provide precise weights for the objects placed on the iPhone 6s' screen, but it can be handy for comparing two or more objects at once to see which one weighs the most.
Aptly titled Plum-O-Meter, which is named after the fruit that is weighed during a demonstration video, the open source app uses the iPhone 6s's 3D touch to display the weights of plums relative to the the phone's maximum possible force. Of course, you don't have to use plums, you can use apples, oranges, fingers, or any other object weighing enough that's capable of being picked up by the capacitive touch screen.