Example of leveraging Sitecore Caching engine in custom code

CacheService.cs

public class CacheService
{
    private const string CacheName = "Custom_Cache"; // a unique name for your cache
    private readonly ICache<string> _cache;

    public CacheService()
    {
        _cache = CacheManager.FindCacheByName<string>(CacheName);
        if (_cache != null) // if cache is already initialized, return out
            return;
        
        // else create a new cache
        _cache = new Cache<string>(CacheName, Sitecore.Configuration.Settings.Caching.DefaultFilteredItemsCacheSize)
        {
            Enabled = true,
            Scavengable = false
        };
    }

    public void AddToCache(string key, object data, DateTime absoluteExpiration)
    {
        if (!_cache.ContainsKey(key))
        {
            _cache.Add(key, data, absoluteExpiration);
        }
    }

    public object GetFromCache(string key)
    {
        return _cache?.GetValue(key);
    }

    // this method can be called from a publish:end event handler to wipe your caches
    public void Clear(object sender, EventArgs args)
    {
        _cache.Clear();
    }
}

CacheService.Events.config

<?xml version="1.0" encoding="utf-8"?>
<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/" xmlns:role="http://www.sitecore.net/xmlconfig/role/" xmlns:set="http://www.sitecore.net/xmlconfig/set/">
  <sitecore>
    <events>
      <!-- clear custom cache when publishing completes -->
      <event name="publish:end">
        <handler type="MySite.Services.CacheService, MySite.Services" method="Clear" />
      </event>
      <event name="publish:end:remote">
        <handler type="MySite.Services.CacheService, MySite.Services" method="Clear" />
      </event>
    </events>
  </sitecore>
</configuration>