Return Policy Apple Pencil

Here is Apple’s definitive compatibility list for Apple Pencil and iPad:

Apple Pencil compatibility - Apple Support

In most countries/regions, if purchased directly from Apple, you have 14-days within which you can return an unwanted item for exchange or refund.

If not purchased from Apple, you will need to check the retailers own returns policy.

That will be between you and the retail source where you ordered it. If Apple, contact the Apple Online Store for your answer. If not Apple, it will depend on that source's return policy. In either case, a refund, if one is forthcoming, may not be immediate.