In VBA, how do I access the text value of an ActiveX text box control on an Excel worksheet?
You can use
ActiveSheet.TextBox1.Text to set or get the contents of an ActiveX textbox control.
If you have more than one ActiveX textbox on a page, you can use
ActiveSheet.OLEObjects("boxname").Object.Text to set or get its contents. boxname is the name of the box in quotes ; or with no quotes, a string variable to which you have assigned the name of the textbox; or the object number of the box.
See this Microsoft documentation for more information.