Picture一个，Timer1一个
    Private Type POINTAPI
    x As Long
    y As Long
    End Type
    
    Private Declare Function GetPixel Lib "gdi32" (ByVal hdc As Long, ByVal x As Long, ByVal y As Long) As Long
    Private Declare Function GetCursorPos Lib "user32" (lpPoint As POINTAPI) As Long
    Private Declare Function GetWindowDC Lib "user32" (ByVal hwnd As Long) As Long
    
    Private Sub Form_Load()
    Timer1.Interval = 100
    End Sub
    
    Private Sub Timer1_Timer()
    Dim tPOS As POINTAPI
    Dim sTmp As String
    Dim lColor As Long
    Dim lDC As Long
    
    lDC = GetWindowDC(0)
    Call GetCursorPos(tPOS)
    lColor = GetPixel(lDC, tPOS.x, tPOS.y)
    Picture1.BackColor = lColor
    
    sTmp = Right$("000000" & Hex(lColor), 6)
    Caption = "R:" & Right$(sTmp, 2) & " G:" & Mid$(sTmp, 3, 2) & " B:" & Left$(sTmp, 2)
    End Sub
    主要利用了GetPixel函数，或者更应该说是API，下面是详细的说明：
    VB声明
    Declare Function GetPixel Lib "gdi32" Alias "GetPixel" (ByVal hdc As Long, ByVal x As Long, ByVal y As Long) As Long
    说明
    在指定的设备场景中取得一个像素的RGB值
    返回值
    Long，指定点的RGB颜色。如指定的点位于设备场景的剪切区之外，则返回CLR_INVALID
    参数表
    参数 类型及说明
    hdc Long，一个设备场景的句柄
    x,y Long，逻辑坐标中要检查的点
    注解
    用GetDeviceCaps判断设备是否支持本函数