Blues had already threatened through Daryl Murphy before Hyam finished off a smart move to put Town ahead with his first goal of the season.
Sammon doubled the advantage with his first goal in Town colours just past the hour but Wigan rallied and Martyn Waghorn set up a grandstand finish with a strike seven minutes from time.
Oriol Riera hit the post with a right foot rocket but Town held on to maintain the drive up the table.
Town made two changes from the side that beat Brighton last week, Hyam coming in for virus victim Jay Tabb, while Sammon started against his former club, Paul Anderson dropping to the bench.
Wigan started brightly and Andy Delort headed over inside the first few minutes, then Don Cowie’s cross was headed clear by Christophe Berra.
Blues responded though and Tyrone Mings got on the end of David McGoldrick’s pass but was forced across goal and couldn’t get his shot in.
Murphy brought an excellent save from Scott Carson with a 25 yard drive, Sammon then flashing a header past the near post before Blues got the breakthrough on 19 minutes, Hyam finishing off a good move with a sidefoot finish from 15 yards.
Town were close to adding a second a minute later, Sammon denied the chance to stab in McGoldrick’s cross by Emmerson Boyce’s challenge.
McGoldrick was then thwarted after Murphy had tried to set him up following Cole Skuse’s excellent pass as Town carved open the Latics’ defence again.
Boyce’s shot was deflected wide for a corner as Wigan threatened for the first time in a 15 minute spell that Blues had dictated, the home side forced into a change just past the half hour with Callum McManaman replaced by James McClean.
Delort headed wide but Blues went into the break ahead and deservedly so after creating the much better chances, with Town keeping Wigan at arms’ length at the other end.
Carson had to be quick off his line to clear from McGoldrick in the opening minutes of the second-half, Adam Forshaw responding for the home side with a shot over the bar from distance.
Kevin Bru replaced the injured Skuse on the hour, the midfielder soon in the action, hooking the ball over the bar from the edge of the area.
Town made it two on 62 minutes, McGoldrick played in Sammon, the Derby loanee was first denied by Carson but reacted quickest and put the ball into the empty net to celebrate right in front of the travelling Blue Army.
Murphy could have made it three soon after, the Republic of Ireland international getting on the end of Hyam’s pass but the ball ran away from him and Carson ended the danger.
McGoldrick weaved his way around the static Latics’ defence but his shot was wide as Blues threatened at every turn, the home side’s fans growing increasingly frustrated.
Darren Ambrose replaced cramp victim Teddy Bishop for his third ‘debut’ for the Club with 20 minutes left on the clock, Dean Gerken called into action to make his first save soon after, the ‘keeper in the right place to keep out Ivan Ramis’ header.
Carson saved from McGoldrick after more trickery from the striker but it was Wigan who struck next, McClean’s shot deflected in by fellow substitute Waghorn three yards out on 83 minutes.
Reira headed at Gerken from 15 yards as Wigan surged forward looking for an equaliser, the striker going even closer with a shot that thundered back off the inside of the post but Town held on for three big points.