Simple trick allows you to use the Apple Pencil on an iPhone or older iPad
The Apple Pencil is a $99.00 accessory originally made for the Apple iPad Pro. It is also now compatible for the 6th generation Apple iPad (2018). So those with an iPhone or an older iPad don't get to experience the capabilities of the Apple Pencil. That is, unless they use a simple trick that will allow the accessory to work with any iOS device. That's right, follow the rules and you'll be able to sketch, take notes, mark up documents and more on your iPhone.
If you don't want to keep damp napkins with you at all times, perhaps this is knowledge you can keep in the back of your head and use it when needed. Of course, you will have to buy an Apple Pencil first.
source: iDeviceHelp
Things that are NOT allowed: