See external documentation: wxCommandEvent.

Use wxEvtHandler:connect/3 with EventType:

command_button_clicked, command_checkbox_clicked, command_choice_selected, command_listbox_selected, command_listbox_doubleclicked, command_text_updated, command_text_enter, command_menu_selected, command_slider_updated, command_radiobox_selected, command_radiobutton_selected, command_scrollbar_updated, command_vlbox_selected, command_combobox_selected, command_tool_rclicked, command_tool_enter, command_checklistbox_toggled, command_togglebutton_clicked, command_left_click, command_left_dclick, command_right_click, command_set_focus, command_kill_focus, command_enter

See also the message variant #wxCommand{} event record type.

This class is derived (and can use functions) from:
wxEvent