How to import vector graphics from OneNote to Inkscape
To transfer your sketches from OneNote to Inkscape, simply select the drawing, then use the copy/paste operation.
This has a side-effect - the pasted objects will have many nodes - making it costly to apply any changes to the image.
You can address that problem by simplifying the object multiple times, in order to reduce the number of nodes. As a result, processing goes somewhat faster.
An alternative is to save OneNote's image to a bitmap, then trace that bitmap with Inkscape. This produces better results, but it is not as easy as a simple copy/paste operation, since you have to perform many intermediate actions in order to get this done.