Since disabled control elements can't have events bound to them, you'd need to bind an event to an ancestor element and make a check to see whether the target was the input.
You can then go on to check if it's disabled, and if so, show your alert:
$(document).on('click',function(e){
if(e.target.id == "Travellerpaymentinfo_cc_number" && e.target.disabled){
alert("The textbox is clicked.");
}
});