In Billing Add custom Checkout field where product name dynamilcally fill

Hi @shailyadav992

Thanks for sharing further information about your end goal here.

I understand you want to add Add custom Checkout field on the site.

What you would like to do can’t be done with the built-in functionalities of WooCommerce. Either you customize the checkout template or install a third-party plugin like Conditional Checkout Fields for WooCommerce.
I have also found this article which could be a good starting point:

https://www.businessbloomer.com/woocommerce-visual-hook-guide-checkout-page/

For more information about how to customize checkout fields, check our article:
Customizing existing checkout field and adding custom checkout fields

Since custom coding is outside our scope of support, I am leaving this thread open for a bit to see if anyone can chime in to help you out.

I can also recommend the WooCommerce Developer Resources Portal for resources on developing for WooCommerce.

You can also visit the WooCommerce Facebook group or the #developers channel of the WooCommerce Community Slack. We’re lucky to have a great community of open-source developers for WooCommerce, and many of our developers also hang out there.

Another option is to check our customizations page to hire an expert that can create a custom solution for you: https://woocommerce.com/experts/