Hi I found the solution. Mainly the problem was getting item from ContentCache by UDI. I have blog and my articles have MNTP which value I need to store in the index. I implement my TransformingIndexValues method:

 public class CustomExamineComponent : IComponent
    {
        private readonly IExamineManager _examineManager;
        private readonly CustomIndexCreator _indexCreator;
        private readonly IUmbracoContextFactory _contextFactory;

        public CustomExamineComponent(IExamineManager examineManager, CustomIndexCreator indexCreator, IUmbracoContextFactory contextFactory)
        {
            _examineManager = examineManager;
            _indexCreator = indexCreator;
            _contextFactory = contextFactory;
        }


        public void Initialize()
        {
            DirectoryFactory.DefaultLockFactory = d =>
            {
                var simpleFsLockFactory = new NoPrefixSimpleFsLockFactory(d);
                return simpleFsLockFactory;
            };
            foreach (var index in _indexCreator.Create())
            {
                _examineManager.AddIndex(index);
                if (index.Name == "NewsSearchIndex")
                {
                    ((BaseIndexProvider)index).TransformingIndexValues += CustomExamineComponent_TransformingIndexValues; 
                }

            }

        }

        private void CustomExamineComponent_TransformingIndexValues(object sender, IndexingItemEventArgs e)
        {
            using (var ctx = _contextFactory.EnsureUmbracoContext())
            {
                var cache = ctx.UmbracoContext.ContentCache;
                if (e.ValueSet.ItemType == "articleDetailsPage")
                {
                    var categoryItem = e.ValueSet.Values["category"];
                    if (categoryItem != null)
                    {                       
                        Udi udi;
                        if (Udi.TryParse(categoryItem[0].ToString(), out udi))
                        {
                            //Get node by UDI
                             var guid = GuidUdi.Parse(udi.ToString());
                             var node = cache.GetById(guid.Guid);
                        }
                    }
                }
            }
        }
    }