Write to Excel ActiveX TextBox C#

Question

I have a C# program, and I want to write C# textbox string to excel ActiveX TextBox.

I can open a sample xlsx, write to cells, export as pdf... But cant write to textbox. I have found another question here, which could be the soultion

(Reach ActiveX or Form objects (textbox) from codebehind in an Excel document)

but I can't using "Microsoft.Vbe.Interop.Forms;", I have only Microsoft.Vbe.Interop;