To find element is present or not

I think WaitElement should be the right method for your case.
It will return a stub object that has only the Exists attribute and its set to false by default.

https://support.smartbear.com/testcomplete/docs/reference/test-objects/members/page/waitelement-method-page-object.html

If this still does return Exists == true then your object probably exists but is not visible.

What you can try is to check for exists and if its true you need to verify that it is not visible.
Or you have to specify your xpath so it will not find the element when its not visible.

Using the Object Browser and enable "Show invisible objects",

Is your UI object appearing in the Object Browser? Your UI object may Exists, but it's property value Visibility is set to False. 

Hi.

To find if an element is present or not I use this script :

function get(page, value, presence = true, scroll = true) {
  const pageElement = utils.getPage(page);
  
  Options.Run.Timeout = 50;
  optimisation.stopLog();
  const elementHTML = pageElement.FindElement(value);
  optimisation.startLog();
  Options.Run.Timeout = 4000;
  
  
  if(presence && elementHTML.Exists) {
    elementHTML.scrollIntoView(scroll);
    Log.Message("On a trouvé l'élément :" + value);
    return true;
  }else if(!presence && !elementHTML.Exists) {
    Log.Message("On a pas trouvé: " + value);
    return true;
  }else{
    Log.Error(`On a ${presence ? "pas " : ""}trouvé: ${value}`);
    return false;
  }
}

stopLog and startLog are important here, because when TC didn't find the object, it return an error. But this error is expected if we want to not find the object. (in my case, I don't want to log this error).

Are you able to post an image similar to this, which shows the Object Browser and Properties for your UI object?