Hi,
I don't understand what you mean by " i want the product custom fields as shipping option for particular product on checkout".
Custom products fields allow the shop owner, or the vendor, to add information to a product.
I don't see the link with the shipping methods selection on the checkout.
Also, on the checkout, the shipping methods selection is for the whole order, not for each product, so in don't understand the "for particular product".
I'm feeling that we're not talking about the same thing here.