public class DumpPcap
{
    public int _interfaceNumber;
    public string _pcapPath;
    public string _dumPcapPath = @"C:Program FilesWiresharkdumpcap.exe";

    public DumpPcap(int interfaceNumber, string pcapPath)
    {
        _interfaceNumber = interfaceNumber;
        _pcapPath = pcapPath;
    }

    public void startTheCapture()
    {
        List<string> stList = new List<string>();
        ProcessStartInfo process = new ProcessStartInfo(_dumPcapPath);
        process.Arguments = string.Format("-i " + _interfaceNumber + " -s 65535 -w " + _pcapPath);
        process.WindowStyle = ProcessWindowStyle.Hidden;
        process.RedirectStandardOutput = true;
        process.RedirectStandardError = true;
        process.CreateNoWindow = true;
        process.UseShellExecute = false;
        process.ErrorDialog = false;
        Process dumpcap = Process.Start(process);
        StreamReader reader = dumpcap.StandardOutput;
        //dumpcap.WaitForExit(100000);

        while (!reader.EndOfStream)
        {
            stList.Add(reader.ReadLine());
        }
    }
}

List<string> stList = new List<string>();

var process = new Process();
process.StartInfo.FileName = _dumPcapPath;
process.StartInfo.Arguments =
    string.Format("-i " + _interfaceNumber + " -s 65535 -w " + _pcapPath);
process.Startinfo.WindowStyle = ProcessWindowStyle.Hidden;
process.Startinfo.RedirectStandardOutput = true;
process.Startinfo.RedirectStandardError = true;
process.Startinfo.CreateNoWindow = true;
process.Startinfo.UseShellExecute = false;
process.Startinfo.ErrorDialog = false;

// capture the data received event here...
process.OutputDataReceived +=
    new DataReceivedEventHandler(process_OutputDataReceived);

process.Start();
process.BeginOutputReadLine();


private void process_OutputDataReceived(object sender, DataReceivedEventArgs arg)
{
    // arg.Data contains the output data from the process...
}