Lost connector for first generation Apple Pencil

The first generation Pencil is charged and paired using the iPad charging cable - and an Apple USB-C to Apple Pencil Adapter:

New first generation Pencils now ship with this special adapter in the box along with the Pencil. However, some older stock purchased from retailers may lack the USB-C to Lightning adapter - and may instead have an older Lightning to Lightning Adapter.

For owners of older first generation Pencils, or for “old stock” new Pencils, the new special adapter is available and can be purchased directly from Apple as an accessory.

https://store.apple.com/xc/product/MQLU3ZM/A

Apple no longer supports that unit. But if you search third party vendors, such as Amazon, for "1st generation apple pencil charger," you will find them for sale under $10.