Can I use my pencil on iPad 2

NO - designed to work with capabilities of the iPad Pro

Will the apple pencil work on ipad air 2 <

It only works with iPad Pro.

http://www.apple.com/shop/product/MK0C2AM/A/apple-pencil-for-ipad-pro

Either return it or upgrade to an iPad Pro.

The clue is in the name of the product: "Apple Pencil for iPad Pro "

The Apple Pencil will only work with the new iPad Pro.

Return the Pencil for a full refund and choose another smart stylus for your iPad.

I use an Adonit smart stylus on my iPad Pro and that works just peachy.

The Adonit stylii will work fine on your iPad model.

http://www.adonit.net/

Good Luck!