Well an ISO is a container that can be burned to a disk or USB or virtually mounted in Windows. A WIM is a windows image container that contains only the files that make up the operating system, but not the required files to boot to a PE environment and apply the WIM so converting them isn't really something you would do.
What you can do is take a copy of the Windows 10 ISO, extract the content, replace the install.wim file with yours and re-package it as an ISO or simply copy that content to a USB drive.