$wp_customize->add_control(
       new WP_Customize_Image_Control(
           $wp_customize,
           'logo',
           array(
               'label'      => __( 'Upload a logo', 'theme_name' ),
               'section'    => 'your_section_id',
               'settings'   => 'your_setting_id',
               'context'    => 'your_setting_context'
           )
       )
   );