How do I grab any selected text from another app. without using of a clipboard ?

Why not use the Clipboard? Next example will get the selected text from Notepad.

Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Private Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" (ByVal hWnd1 As Long, ByVal hWnd2 As Long, ByVal lpsz1 As String, ByVal lpsz2 As String) As Long
Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare Function GetWindowText Lib "user32" Alias "GetWindowTextA" (ByVal hwnd As Long, ByVal lpString As String, ByVal cch As Long) As Long
Const WM_COPY = &H301
Const WM_PASTE = &H302

Private Sub Command1_Click()
    Dim hParent As Long
    Dim hChild As Long
    Dim strTemp As String
    
    hParent = FindWindow("Notepad", vbNullString)
    hChild = FindWindowEx(hParent, 0&, "Edit", vbNullString)
    SendMessage hChild, WM_COPY, 0, 0
    SendMessage Text1.hwnd, WM_PASTE, 0, 0
End Sub