Laravel Many to Many Relationship with 2 foreign key - laravel

Question

I have 3 tables - users, graduation_institutes, graduation_degrees
I defined a pivot table - graduation_degree_user
graduation_degree_user table has data like below -
id--------doctor_id--------graduation_degree_id----------graduation_institute_id---------year
In my User model, I defined relation like below -
public function graduations(){
return $this->belongsToMany('App\Models\User\GraduationDegree')->withTimestamps();
}
In my controller, I m doing -
if($request->has('graduations')){
$user->graduations()->sync($request->graduations);
}
return $user->graduations;
Where graduations is an array which contains multiple object.
I am getting the following response -
[
{
"id": 3,
"degree": "MD",
"created_at": null,
"updated_at": null,
"pivot": {
"user_id": 2,
"graduation_degree_id": 3,
"graduation_institute_id": 1,
"created_at": "2020-12-01T07:54:23.000000Z",
"updated_at": "2020-12-01T07:54:23.000000Z"
}
},
{
"id": 4,
"degree": "MBBS",
"created_at": null,
"updated_at": null,
"pivot": {
"user_id": 2,
"graduation_degree_id": 4,
"graduation_institute_id": 2,
"created_at": "2020-12-01T07:54:24.000000Z",
"updated_at": "2020-12-01T07:54:24.000000Z"
}
}
]
In response, I am getting graduation_institute_id but I also want the name of the institute which is a field 'institute' defined in graduation_institutes table.