show_news-events-by-cat

// WP_Query arguments
$args = array(
	'tax_query'              => array(
		'relation' => 'OR',
		array(
			'taxonomy'         => 'category',
			'terms'            => 'high_school',
			'field'            => 'name',
			'operator'         => 'IN',
			'include_children' => true,
		),
		array(
			'taxonomy'         => 'tribe_events_cat',
			'terms'            => 'high_school',
			'field'            => 'name',
			'operator'         => 'IN',
			'include_children' => true,
		),
	),
);

// The Query
$show_news-events-by-cat_query = new WP_Query( $args );

// The Loop
if ( $show_news-events-by-cat_query->have_posts() ) {
	while ( $show_news-events-by-cat_query->have_posts() ) {
		$show_news-events-by-cat_query->the_post();
		// do something
	}
} else {
	// no posts found
}

// Restore original Post Data
wp_reset_postdata();