How can I use Delphi code from a C# application?

I have a Delphi project, and I need to write a C# application, but I want to use some functions from this Delphi project. I haven't worked in Delphi before.

I found that I can create a DLL from the Delphi code and use it directly in C#. How can I do that? Or I also found some conversion tools to convert to C#, but it wasn't so good. So what is the best way? DLL or convert?