There is no way how you can actually convert iso to exe, i.e. ISO disk image (.iso) to Windows Executable format (.exe). Nevertheless, there are some procedures that achieve something similar, although it is not the actual iso to exe conversion per se.
Some users just want to launch some executable from the ISO and wonder how. For these, best option is to simply extract the ISO. Or if you are using Windows 8 or later, you can simply mount your .iso image and launch it from there. This can also be done with any 3rd party virtual CD/DVD drive like Daemon Tools.
Another way how to achieve iso to exe transformation, is to compress it via some file archiver utility to a self-extracting archive, that also has EXE. Executing that archive would decompress the ISO. This can be done in programs like WinRAR or similar.Open ISO file Open EXE file