Is there pen available for iPad 4th generation?

The Apple Pencil is for the pro only, but there are styli out there that work. Wacom makes one, so does Bamboo and others.

http://www.macworld.co.uk/feature/ipad/best-stylus-for-ipad-choose-ipad-stylus-f rom-these-10-options-3586503/

is an article giving you some to research

If you're just looking for your average rubber tipped pointer styli, then any soft rubber tipped one will do...and they are very affordable, like $5 or less