COnverting windows application to service

I think there is no tool or conversion option by which you can straight away convert a win forms application to a service,

because windows forms has events like mouse click, key press associated with UI action, which a service can be executed based on a call from client.

 

If I was you, what I will do is I will extract all business logic in a separate class library and make use of that library in windows forms app and use same library to create a service.

 

This way only logic relevant to UI actions is in windows form app, all other logic is in different library which can be called from anywhere.