No, only using QV 10. I saw in 'Whats new in QV10' guide:
Where can I see tags and comments?
You can see tags and comments in the table viewer (hover on field); settings > document
properties > tables (list of fields); select field dialog (hover on field); and chart dimension
selection dialog (hover on field).
But, we don't have any field dialog and chart dimenion selection dialog?
OK, in QV 10 this functionality seems to be there only as a reminder to the designer what the expression is all about, not as something to be shown to the user when you hover over the column name of the chart. From QV10 manual:
This is a commentary field where the creator of the expression can
describe the purpose and function of the expression. By clicking the
… button the full Edit Expressiondialog is opened.
If you want to have the expression comments visible in the way you describe, update to QV 11 and you'll see them when you hover.