Born in
Arafat in the outskirts of
Nouakchott, Hacen started off at local
ASAC Concorde and nearly moved to
Valencia CF in August 2014 after impressing in the year's
L'Alcúdia International Football Tournament, but chose to join
Levante UD instead. However, he was unable to play any official matches until his 18th birthday. Assigned to the club's
Juvenil squad, Hacen made his debut with
the reserves on 14 January 2016, coming on as a first half
substitute in a 1–3
Segunda División B away loss against
CD Llosetense. He was definitely promoted to the B-side ahead of the
2016–17 campaign, and scored his first senior goal on 6 November to open a 2–0 home win over
UE Llagostera. Hacen made his first team debut on 28 November 2017, starting in a 1–1 home draw against
Girona FC, for
the season's
Copa del Rey. His
La Liga debut occurred three days later, replacing
Samu García in a 0–0 away draw against
Málaga CF. On 24 July 2018, Hacen signed a two-year deal with another
reserve team,
Real Valladolid B also in the third division. He made one two-minute substitute appearance for the
first team in the top flight the following 23 April, a 1–0 win over
Girona FC at the
Estadio José Zorrilla. On 31 January 2020, Hacen was loaned to
Segunda División side
CD Lugo for the remainder of
the campaign. He scored his first professional goal on 16 February, netting the game's only in an away success over
CF Fuenlabrada. On 2 October 2020, Hacen rejoined Lugo on loan for the
2020–21 campaign. Upon returning, he suffered a
knee injury in July 2021 while on international duty, and later terminated his contract with Valladolid the following 30 January. On 26 August 2022, after roughly one year of inactivity and six months without a club, Hacen returned to Lugo on a permanent one-year contract. ==International career==