get selected value from checkedlistbox c# windows application

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C#

hi

I try to get value for checked items in checklistbox
my problem is when I used timer to get value each minutes
invoke required ?
how can I solve this issue

for (int i = 0; i < ContactsList.Items.Count; i++)
                if (ContactsList.GetItemCheckState(i) == CheckState.Checked)
                {
                    string mobileNo = ContactsList.Invoke(new MethodInvoker(delegate { ContactsList.SelectedValue[i]; }));
                }