Take the Stabilo Digipen, for example. Unveiled last week at CES 2016, the Digipen is an ordinary looking ink pen that is packed with sensors and can pair with your computer or mobile device over Bluetooth.
As you write your notes on paper, the Digipen sends data to your device so that the companion app can translate your handwritten notes into digital text. It requires some training before it learns to recognize a user's writing, and is mainly intended to convert to text.
Shapes like squares and circles can also be recognized, but this is more of a text-grabbing tool than a sketching implement. But even with that limitation, this could be a great tool for those of us who won't give up our paper notebooks.
And of course there's always room for improvement. The Digipen has sensors which measure acceleration, rotation, and movement, and it also has a 2048-level pressure sensor monitoring the tip. With a little work on the software, we might be able to use this as a sketching tool.
Stabilo plans to launch the Digipen later this year in a crowd-funding campaign. They're planning to charge around 100 euros, or about what Apple is asking for that ridiculous Apple Pencil.