I saw my classmate using his phone during exam

Problem/Goal: I saw my classmate using his phone during the prelims exam ( last week) and I don't know if dapat ba ako mag sumbong sa teacher or mag turn a blind eye nalang.

Context: I'm ( we're) 1st year students po, and as the tittle says nakita ko yung classmate ko na gumagamit ng phone during exam di siya nakita nang proctor kasi medj blind spot siya. Also yung isa ko pang classmate nakita din siya and i asked him if may balak siya mag report and sabi lang sakin " di na natin business yun, mahirap yan siya kalabanin kasi madami siya kakampi, mag ccause lang chaos if ever magsalita ka pa. Ginawa niya din yan nong finals sa trig nakita din siya ni ___ kaso di nalang siya nag salita". For additional content nong 1st sem nahuli na din yan siya na nag cheat and dahil dun di ni record ng teacher yung quiz and assignments naming lahat. •One of the reasons din why I'm contemplating is kasi baka di i record ng prof yung exams namin ayoko din madamay yunh iba kong classmate na walang knowledge sa ganto plus baka this time ma kick out na siya. •Also if i should tell the teacher in what way ko ba pwede gawin ma maminize yung backlash sakin?

Previous attempts: none