Go to View>Show and Erase and select 'axis' (you can sort by feature or view). This will place axis and centre marks on the part where relevant. You can then dimention from the axis of the bottom hole to the crosshair on the top hole (on the same view, left hand side). If you want to have a dimention attached to both views, you will just have to try it, I don't know what would happen, not sure if you can dimension from one view to another but at least you will be able to place the dimension you want.