change
Fires when the value is changed

Example

$("#numeric").kendoNumericTextBox({
    change: function(e) {
        // handle event
    }
});

To set after initialization

// get a reference to the numeric textbox widget
var numeric = $("#numeric").data("kendoNumericTextBox");
// bind to the change event
numeric.bind("change", function(e) {
    // handle event
});
spin
Fires when the value is changed from the spin buttons

Example

$("#numeric").kendoNumericTextBox({
    spin: function(e) {
        // handle event
    }
});

To set after initialization

// get a reference to the numeric textbox widget
var numeric = $("#numeric").data("kendoNumericTextBox");
// bind to the spin event
numeric.bind("spin", function(e) {
    // handle event
});