What should I do if I received a wrong Apple Pencil model?

Go back to the store(Apple generally offers returns on hardware within 14 days) or sell it to someone else.

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

Apple Pencil compatibility - Apple Support

Select Apple Pencil - Apple

If you have been supplied with the incorrect Pencil for your iPad, you will need to return it to your retailer for exchange or refund.