A neat way of taking advantage of the big screen of the iPhone is with a capacitive stylus which not only gives your index finger a break, but also adds a different dimension to drawing and writing! The Apple Pencil is a popular choice but it only works with the iPad Pro despite the fact that even older iPhone models like the iPhone 6S and 6S Plus have a pressure-sensitive display layer to enable 3D Touch.
A good alternative to the Apple Pencil is the Adonit Snap 2 stylus which works with the iPhone 6 (and newer models) and doesn't require to be paired via Bluetooth like the Apple Pencil does.
There is neither a tapping noise with the Adonit Snap 2 stylus which you get with the Apple Pencil so you can take notes in a school class or university lecture without making a clicking noise when tapping onto the iPhone glass screen.

Another neat feature you get with the Adonit Snap 2 stylus is a Bluetooth shutter remote that lets you operate the built-in camera app on the iPhone so you can take selfies remotely.
The Snap 2 stylus can trigger both the selfie camera and rear camera of the iPhone, and lets you take a triple burst photo capture (three continuous shots) as well as a standard single shot photo. The Snap 2 shutter remote also works within photo apps such as ProCamera 8, Hipstamatic, SnapChat and Instagram. Basically, you can use Snap 2 with any finger writing apps.
Unlike most styli which have a rounded body like a fountain pen, the Adonit Snap 2 has a flat 4.3mm aluminum body without the clear disc you find in other styluses such as the Droid Stylus, Pro 3 Stylus and Mini 4 Stylus. The convenient thing about the Snap 2 tip is that you won't have to replace it because it is made from a strong thermoplastic.
The Adonit Snap 2 pixelpoint tip has a 1.9mm precise diameter so it works great for writing notes and freehand drawing. The fine point tip of the Snap 2 is similar in size to that of the Samsung Note 5 S Pen so you get a pen-like tip that it's easier to write or draw with than with a thick tip stylus.
With that said, thick glossy screen protectors don't work as well with the Adonit Snap 2 stylus like PET (polyethylene terephthalate) screen protectors.
Adonit Snap 2 is a powered capacitive stylus so there is a small battery inside the housing that can deliver continuous power for 7 hours. Recharging is easy via the micro USB port located on the back of the Adonit Snap 2.
A micro USB cable is included too. Full charge takes 60 minutes and there is also a sleep-mode that automatically turns off the Snap 2 stylus after 15 minutes of inactivity (to wake up the stylus press the button).
There is an led indicator light and a single button located on the front of the Adonit Snap 2 which doubles as the power and shutter remote button when the Snap 2 is connected to your phone through Bluetooth 4.0.
When you're done using the Snap 2 stylus pen, you can store it behind your iPhone thanks to the built-in magnet. Included is a 0.4 mm metal plate that you stick on the back of your phone so the metal body of the Snap 2 stylus can attach to it (the magnet is located mid-way). Check out the review of the Adonit Note-M Mouse Pen.