在C#中實現WinPcap的多線程操作可以通過使用異步操作和多線程來實現。下面是一個簡單的示例代碼：

using System;
using System.Threading;
using System.Threading.Tasks;
using PcapDotNet.Core;

class Program
{
    static void Main()
    {
        Task.Run(() => StartCapture());
        
        // Do other tasks in the main thread
    }

    static async Task StartCapture()
    {
        using (PacketDevice selectedDevice = LivePacketDevice.AllLocalMachine[0])
        {
            using (PacketCommunicator communicator = selectedDevice.Open(65536, PacketDeviceOpenAttributes.Promiscuous, 1000))
            {
                communicator.SetFilter("tcp");

                while (true)
                {
                    Packet packet;
                    PacketCommunicatorReceiveResult result = communicator.ReceivePacket(out packet);

                    if (result == PacketCommunicatorReceiveResult.Timeout)
                    {
                        // Handle timeout
                        continue;
                    }

                    // Process the received packet
                    Console.WriteLine($"Received a packet with length {packet.Length}");
                }
            }
        }
    }
}

在上面的示例中，我們使用Task.Run()方法在另一個線程中啟動了StartCapture()方法。在StartCapture()方法中，我們使用PacketDevice和PacketCommunicator類來捕獲網絡數據包，并在一個循環中不斷接收和處理數據包。這樣就可以在一個單獨的線程中進行網絡數據包的捕獲操作，而不會阻塞主線程的其他任務。