NLogCaller.cs

using System.Runtime.CompilerServices;
using NLog;

namespace NLogCallerName
{
    class Program
    {
        static void Main(string[] args)
        {
            var logger = LogManager.GetLogger("My Log");
            logger.LogCaller(LogLevel.Trace, "Gues who");
        }
    }

    public static class NLogExtensions
    {
        public static void LogCaller(this ILogger logger, LogLevel level, string message, [CallerMemberName] string caller = null)
        {
            var header = caller == null ? "" : $"{caller}: ";
            logger.Log(level, $"{header}{message}");
        }
    }
}