Is it or Will it be possible to insert notes in dorico by the use of an external tablet and pencil?
It is not possible, and it is not something I would expect to be available imminently. If this is very important to you, I suggest you look into StaffPad, which does allow handwriting input and which can send data to Dorico by way of MusicXML.
You mean, without a third party application? Otherwise, it’s already possible. But requires the “import XML” step. The devs have already said that this is not among the priorities, so if you need it now (or in a short term) consider using a third party app 
Ninja’d by Daniel himself! I’m happy I did not answer anything wrong here ^^
Thank you guys, I’m not in a hurry, it’s just that I think that this function (without the use of third part apps) if well implemented could be a game changer.
I use Notion Pro on iPad and I wish that its handwriting technology was implemented on a computer based software. I understand that this is not on the priority list… but I hope you guys think about it seriously. I really believe that the chance to write directly on dorico from the tablet by hand in a similar way Staffpad does would give us a huge improvement in terms of speed and workflow
I didn’t know that staffpad is finally available for apple as well btw!