VBA

EPPlus supports Creating, Reading and Writing VBA. Execution/Interpretation of VBA code is not supported.
A VBA project is created by the CreateVBAProject() method of the ExcelWorkbook class. This enables you to write VBA code to the project as shown in Sample 21-.NET Framework or Sample 21-.NET Core )...

        private static void VBASample1(DirectoryInfo outputDir)
        {
            ExcelPackage pck = new ExcelPackage();
            //Add a worksheet.
            var ws=pck.Workbook.Worksheets.Add("VBA Sample");
            ws.Drawings.AddShape("VBASampleRect", eShapeStyle.RoundRect);            
            //Create a vba project             
            pck.Workbook.CreateVBAProject();
            //Now add some code to update the text of the shape...
            var sb = new StringBuilder();
            sb.AppendLine("Private Sub Workbook_Open()");
            sb.AppendLine("    [VBA Sample].Shapes(\"VBASampleRect\").TextEffect.Text = \"This text is set from VBA!\"");
            sb.AppendLine("End Sub");
            pck.Workbook.CodeModule.Code = sb.ToString();            

            //And Save as xlsm
            pck.SaveAs(new FileInfo(outputDir.FullName + @"\sample15-1.xlsm"));
        }

Remember that the package must be saved with the extension xlsm.
You can also sign your VBA code with a code signing certificate.
Somthing like this...

            X509Store store = new X509Store(StoreLocation.CurrentUser);
            store.Open(OpenFlags.ReadOnly);   
            foreach (var cert in store.Certificates)
            {
                if (cert.HasPrivateKey && cert.NotBefore <= DateTime.Today && cert.NotAfter >= DateTime.Today)
                {
                   pck.Workbook.VbaProject.Signature.Certificate = cert;
                   break;
                }
            }

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See Sample 21 for .NET Core or .NET Framework