Hi Ajoy,
You can use below syntax for it. You can replace www.google.com with your URL.
="<a href=\"www.google.com\" title=\"\" target=\"_blank\" nav=\"web\">insert comment</a>"
Now right click on the cell and go to Linking and Mark "Read content as Hyperlink". Then you can see insert comment as hyperlink and when you click, it will directed to the target URL.
Regards
Rakesh