Your Apple Pencil that comes with the iPad can be charged simply by connecting it to the iPad itself.
1. To charge an iPad Pencil, remove the cap on the top of the pencil and plug it into the slot below the home button.
2. If the pencil has not previously been used on your iPad, make sure you select “Pair” after plugging the iPad pencil in.
The iPad Pencil should now begin charging as long as it remains plugged into the iPad.