This looks promising. And although it sounds like an Apple developer framework, Notekit is a neat looking note taking application. At its core, Notekit is a markdown editor and file management interface. Where it begins to claw at solutions like OneNote or Evernote is with its drawing capabilities. With the exception of xournal++ (née xournal), I don't know of many Linux supporting applications that support drawing/handwriting, though xournal++ is a handwriting application first and foremost, whereas Notekit comes from the other direction.
This project is in “late alpha” quality. So here's your chance to make your contributions to this project at its infancy and shape its development.