Apple's newly announced iPhone Duo will support the Apple Pencil, marking the first time the stylus has worked with an iPhone rather than being restricted to iPads. This is a notable shift for Apple, which originally justified the iPhone's lack of stylus support by arguing it wasn't a good input method, and it reflects the more iPad-like, dual-screen nature of the folding Duo device.

However, the feature comes with significant caveats. Pencil support won't be available at launch, requiring a software update expected around iOS 27.2 in November, after the Duo ships with iOS 27.1 in October. Only the Apple Pencil USB-C model is compatible, meaning owners of the Apple Pencil 2 or Pencil Pro would need to buy an additional $79 stylus, likely because the iPhone lacks the magnets needed for wireless attachment and charging, requiring a USB-C cable instead. The Pencil will work across both the Duo's inner and outer screens, though the cheaper USB-C model lacks features such as pressure sensitivity, double-tap gestures, haptic feedback and Find My support found on the Pencil Pro.