I converted a project from vb6 to vb.net where I found a given control that was inside a TabControl via the collection Controls as such
You can use
Me.Controls.Find("name", True) to search the form and all its child controlsto find controls with given name. The result is an array containing found controls.
Dim control = Me.Controls.Find("textbox1", True).FirstOrDefault() If (control IsNot Nothing) Then MessageBox.Show(control.Name) End If