Hi Sarika,
Thanks for get in touch with us.
I just want to clarify one thing to you.
WCfM custom fields are for capturing additional data when you are creating a Product from Front-end.
But, for display those or how to use those in Single Product page is not part of WCfM.
If you are adding custom fields for a third party plugin then it will show those fields for you. But you have created your own fields then you have to use those using your code.
It’s very simple also, just over ride WC single-product.php in your child theme and display those Fields where you want.
If you have any further queries feel free to share with us.
Thank you