Program.cs

using System;
using System.Text;
using System.Runtime.InteropServices;

namespace Sqlite3Test
{
	public class Program
	{
		public static void Main()
		{
			Console.WriteLine("Loaded libsqlite3 version: " + NativeMethod.sqlite3_libversion() );
		}
	}

	public static class NativeMethod
	{
		[DllImport("sqlite3", EntryPoint = "sqlite3_libversion", CallingConvention = CallingConvention.Cdecl)]
        private static extern IntPtr sqlite3_libversion_raw();

        public static string sqlite3_libversion() => PtrToStringUTF8(sqlite3_libversion_raw());

        public static string PtrToStringUTF8(IntPtr ptr)
        {
            if (ptr == IntPtr.Zero)
            {
                return null;
            }

            var i = 0;
            while (Marshal.ReadByte(ptr, i) != 0)
            {
                i++;
            }

            var bytes = new byte[i];
            Marshal.Copy(ptr, bytes, 0, i);

            return Encoding.UTF8.GetString(bytes, 0, i);
        }
	}
}

project.json

{
	"frameworks": {
		"dnx451": {}
	}
}