Drawing annotations over mapbox map

I am using Mapbox as my mapping library. I am trying to add a functionality where after the map has been rendered completely, the user can draw an annotation and add a comment for it (see image). Now, these annotation details (drawn line coordinates and message) should be saved into my GeoJSON, so that next time when the user reloads the map, it should show the same annotation.

Now I didn't find native support in mapbox for annotation. So not sure how to implement this.

Is there any way to draw annotations over the map after the map is rendered?