I am able to retrieve a page with inkML data from OneNote API as described here:
https://developer.microsoft.com/en-us/onenote/blogs/onenote-ink-beta-apis/
When the page is retrieved via the api (page data and inkML data). How do I know the X, Y position (see image) of the inkml data to present it in relation to the textual data from that page?
The way you have drawn the page is correct. The info retrieved from the API is in the format
<inkml:trace xml:id="st0" contextRef="#ctxCoordinatesWithPressure" brushRef="#br0">1423 7569 3456,x,y,F,etc.
Where x and y co-ordinates have their origin from the top left of the page (f is pressure). Check the following InkMLjs github page for an example implementation dragdrop.html + inkml.js. Just save your retrieved (or generated) InkML data and drop it into the dragdrop.html webpage to display it.