
I think that the ActiveX control should have a name. For example, if you insert a textbox, then its name is TextBox1, which can be seen or changed in Name Box field of Excel. You can also enable the Design Mode, select the ActiveX and press the Properties button from Developer tab. Then you can edit the name.
To access the control, use its name, for example: text = TextBox1.Text
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Show some details if your case is different.