How to join two tables in Asp.net core.

Hi Team,

Unable to retrieve the data from two tables. 

        private readonly CoreDbContext _context;

        public SecSubmodulesController(CoreDbContext context)
        {
            _context = context;
        }

[HttpGet]
        public async Task<ActionResult<IEnumerable<SecSubmodules>>> GetSecSubmodules()
        {
            //return await _context.SecSubmodules.ToListAsync();

            var varSubmodulesData = (from P in _context.SecSubmodules
                                             join C in _context.SecModules on
                                                P.ModuleId equals C.ModuleId

                                             select new SubModules
                                             {
                                                 ModuleID = (long)P.ModuleId,
                                                 SubModuleID = P.SubModuleId,
                                                 ModuleName = C.ModuleName,
                                                 SubModuleName = P.ModuleName,
                                                  
                                             });

            return await varSubmodulesData.ToListAsync();
        }

internal class SubModules
    {
      //

        public long ModuleID { get; set; }
        public string ModuleName { get; set; }
        public string SubModuleName { get; set; }
        public long SubModuleID { get; set; }
         
    }

Error:

Severity	Code	Description	Project	File	Line	Suppression State
Error	CS0029	Cannot implicitly convert type 'System.Collections.Generic.List<sample.Controllers.SubModules>' to 'Microsoft.AspNetCore.Mvc.ActionResult<System.Collections.Generic.IEnumerable<sample.Models.SecSubmodules>>'	sample	D:\Angular\Service_sample \sample \Controllers\SecSubmodulesController.cs	42	Active