Sub test()
  Dim t$: t = Range("A1")
Range("A1") = Replace(t, Mid(t, 1, 1), UCase(Mid(t, 1, 1)))
End Sub

Function uuu$(t$)
    With CreateObject("VBScript.RegExp"): .Pattern = "^."
        uuu = .Replace(t, UCase(.Execute(t)(0)))
    End With
End Function 

Range("A1").Value = UCase(Left(t, 1)) & Mid(t, 2)

Sub test2()
    Dim z, i&
    With CreateObject("ScriptControl")
        .Language = "JScript"
        .AddCode "function g(t){return t.replace(/^[а-яё]/m,function(t1){return t1.toUpperCase()})}"
        z = Range("A1:A" & Range("A" & Rows.Count).End(xlUp).Row).Value
        For i = 1 To UBound(z)
             z(i, 1) = .Run("g", z(i, 1))
        Next
       Range("A1:A" & Range("A" & Rows.Count).End(xlUp).Row).Value = z
    End With
End Sub

Sub test3()
  Dim t$: z = Range("A1:A" & Range("A" & Rows.Count).End(xlUp).Row).Value
 With CreateObject("VBScript.RegExp"): .Pattern = "^[a-zа-яё]"
 For i = 1 To UBound(z)
       z(i, 1) = .Replace(z(i, 1), UCase(.Execute(z(i, 1))(0)))
       Next
    End With
    Range("A1").Resize(UBound(z), 1).Value = z
End Sub