这是使用Keyboard Hook 的范例，它的解释请查VB5 Call WinAPI技巧或Hook的简介 
'以下在.Bas 
Option Explicit 

Declare Function SetWindowsHookEx Lib "user32" Alias "SetWindowsHookExA" (ByVal idHook As Long, ByVal lpfn As Long, ByVal hmod As Long, ByVal dwThreadId As Long) As Long 
Declare Function UnhookWindowsHookEx Lib "user32" (ByVal hHook As Long) As Long 
Declare Function CallNextHookEx Lib "user32" (ByVal hHook As Long, ByVal ncode As Long, ByVal wParam As Long, lParam As Any) As Long 

Public hnexthookproc As Long 
Public Const HC_ACTION = 0 
Public Const WH_KEYBOARD = 2 

Public Sub UnHookKBD() 
If hnexthookproc <> 0 Then 
UnhookWindowsHookEx hnexthookproc 
hnexthookproc = 0 
End If 
End Sub 
Public Function EnableKBDHook() 
If hnexthookproc <> 0 Then 
Exit Function 
End If 
hnexthookproc = SetWindowsHookEx(WH_KEYBOARD, AddressOf _ 
MyKBHFunc, App.hInstance, 0) 
If hnexthookproc <> 0 Then 
EnableKBDHook = hnexthookproc 
End If 
End Function 
Public Function MyKBHFunc(ByVal iCode As Long, ByVal wParam As Long, ByVal lParam As Long) As Long 
'这三个参数是固定的，不能动，而MyKBHFunc这个名称只要和 
'SetWindowsHookex()中 AddressOf後的名称一样便可，不一定叫什麽 
'wParam 是传入按了哪个key的virtual-key code 

'如果您将以下的两行unmark则所有键盘的输入皆没有作用 
'MyKBHFunc = 1 '吃掉信息 
'Exit Function 

MyKBHFunc = 0 '信息要处理 
If iCode < 0 Then 
MyKBHFunc = CallNextHookEx(hnexthookproc, iCode, wParam, lParam) 
Exit Function 
End If 
If wParam = vbKeySnapshot Then '侦测 有没有按到PrintScreen键 
MyKBHFunc = 1 '在这个Hook便吃掉这个信息 
Debug.Print "haha" 
Else 
Call CallNextHookEx(hnexthookproc, iCode, wParam, lParam) 
End If 
End Function 

'以下在Form 
Private Sub Form_Load() 
Call EnableKBDHook 
End Sub 

Private Sub Form_Unload(Cancel As Integer) 
Call UnHookKBD 
End Sub