Pass Value of combobox selected in Userform as input to textbox of other userform

Your description is not very complete but here is a response at the same level as your description.

In the code module for userform1, you will need the following code. You will have logic to insert some value in the text box based on the combo box value.

Private Sub combobox1_Change() ' replace red text with the name of your combobox
   If combobox1.Value = <some value selected by user>
      userform2.textbox1 = <whatever value you want this to be> ' replace red text with the name of your textbox
   End If
End Sub