How do I add information from javascript variables to Django ModelForm input?

I am building a web application using Django. The page shows a large leaflet map, in which users can select one out of several layers. I want users to be able to select a layer, click on the map and add a note to that location and that layer.

I've created a model form, which holds the note itself. This works fine, and saves to my database. However, I need to also include the currently selected layer and mouse-click-location, which is readily available as a JS variable. How do I pass this on in Django?

My views.py holds the following:

if request.method == 'POST':
        form = MapNoteForm(request.POST)
        if form.is_valid():
            form.save()
    else:
        form = MapNoteForm()

And forms.py:

class MapNoteForm(forms.ModelForm):
    note = forms.CharField()

    class Meta:
        model = MapNote
        fields = ('note',)

Finally, the relevant section of the template:

  map.on('click', function (e) {
      var MapNote = L.popup();
      var content = '<form method="post"> {% csrf_token %} {{form}} <br> <button type="submit"> Save</button>'
      MapNote.setContent(content);
      MapNote.setLatLng(e.latlng); //calculated based on the e.layertype
      MapNote.openOn(map);
      })

I'm kind of looking to reverse the workings of the Django-view, trying to pass something from the template to Django, instead of vice versa. What would be the best approach here?