how can i recover an object -  looking up on a property - out of an array of custom objects ?

$collaborators = Import-Csv $PSScriptRoot/collaborateur.csv -Delimiter ';' 

$PeopleInObjects = @()

foreach($collabo in $collaborators)
{
    $pObject = New-Object  PSObject

    $pObject | Add-Member -MemberType NoteProperty "Matricule"       $collabo.Matr
    $pObject | Add-Member -MemberType NoteProperty "Firstname"       $collabo.Prenom
    $pObject | Add-Member -MemberType NoteProperty "LastName"        $collabo.Nom
   

    $PeopleInObjects += $pObject 
}