How to read a macro enabled excel(.xlsm) file using open XML

You can use Free Spire.XLS library to read .xlsm files.

https://www.e-iceblue.com/Download/download-excel-for-net-free.html

It is also available on nuget:

https://www.nuget.org/packages/FreeSpire.XLS/

using Spire.Xls;  
  
namespace ReadXlsm  
{  
    class Program  
    {  
        static void Main(string[] args)  
        {  
            Workbook workbook = new Workbook();  
            workbook.LoadFromFile("Macro.xlsm");  
  
            Worksheet sheet = workbook.Worksheets[0];  
  
            string value = sheet.Range["A1"].Text;  
        }  
    } 
}