https://docs.microsoft.com/en-us/archive/msdn-magazine/2003/july/net-column-calling-win32-dlls-in-csharp-with-p-invoke

figure01.cs

namespace Wintellect.Interop.Sound
{
    using System;
    using System.Runtime.InteropServices;
    using System.ComponentModel;

    sealed class Sound
    {
        public static void MessageBeep(BeepTypes type)
        {
            if (!MessageBeep((UInt32) type))
            {
                Int32 err = Marshal.GetLastWin32Error();
                throw new Win32Exception(err);
            }
        }

        [DllImport("User32.dll", SetLastError=true)]
        static extern Boolean MessageBeep(UInt32 beepType);

        private Sound(){}
    }

    enum BeepTypes
    {
        Simple = -1,
        Ok = 0x00000000,
        IconHand = 0x00000010,
        IconQuestion = 0x00000020,
        IconExclamation = 0x00000030,
        IconAsterisk = 0x00000040
    }
}

snippet01.cpp

BOOL MessageBeep(
    UINT uType // beep type
);

snippet02.cs

[DllImport("User32.dll")]
static extern Boolean MessageBeep(UInt32 beepType);