Q: Apple pencil charging adapter

I don't believe they are currently available for sale.

I Actually have one. A blue one and it works perfectly! You can't either get it from your nearest mall or staples or best buy. The one negative quality about it is that you actually have to charge it first for about 2 hours before you plug it in your phone but other than that it's really good

Re: Where can I buy the apple pencil charging adapter

I Think this link could be helpful.

you can buy adapters on Apple website under Accessories  

It's Apple P/N 923-00817 and costs about five bucks plus another five for S&H from Apple Care.  Amazon sells a USB to female Lightning connector cable in case that's easier (also 10 bucks).