You can use the Sys.ObjectFromPoint method to do this. For example (JScript):
<font class="small">Code:</font><hr /><pre>var obj = Sys.ObjectFromPoint(Sys.Desktop.MouseX, Sys.Desktop.MouseY);
If you need to check whether TC clicked an object at run time, you can handle the OnLogEvent event (see the "Handling Events With TestComplete" and "OnLogEvent Event" help topics). When an object is clicked, TC posts information about that to the log. By checking the posted event's text, you can decide whether it is an 'object clicked' event or not and take some actions if it is.
If you mean something else, please describe what you're trying to do in detail.
There's no way to do this. The only thing I can suggest is to put an object picker on the form (see the "TObjectPicker Object" help topic). Your users can capture objects with it and select the action to be performed from the list located on the same form.