C# Calling VBA

link - learn.microsoft.com/en-us/visualstudio/vsto/combining-vba-and-document-level-customizations 
link - learn.microsoft.com/en-us/visualstudio/vsto/how-to-expose-code-to-vba-in-a-visual-csharp-project 
link - learn.microsoft.com/en-us/visualstudio/vsto/walkthrough-calling-code-from-vba-in-a-visual-csharp-project 

CallVSTOAssembly

EnableVbaCallers