Raise custom event in form

[venerable bede]

I have a form which contains an object :

public IDataItem _objCurrent
        {
            get
            {
                return objCurrent;
            }
            set
            {
                objCurrent = value;
            }
        }

I also have a timer_tick event :

private void timer1_Tick(object sender, EventArgs e)
        {
            clsAPI lclsAPI = new clsAPI();
            lclsAPI.apiGetCurrent(this.objCurrent);
        }

The cut down method in my clsAPI looks like this :

public AdapterTest.IDataItem apiGetCurrent(IDataItem current)
        {
    
            if (dItem == current)
            {
                break;
            }
            else
            {
                //RAISE EVENT IN FORM BUT HOW ?;
            }
            
        }

Basically if the objects do NOT equal eachother I want to raise an event in the form to do something but the question is how.