Southern Vipers 115 for 6 (McCaughan 42, Adams 36) beat Thunder 111 by four wickets
Batter McCaughan hadn't featured in Vipers' opening three matches but made the most of Maia Bouchier and Danni Wyatt's England call-ups with five boundaries on her way to her highest T20 score for Vipers.
"It was nice to get an opportunity at the top of the order," McCaughan said. "I've been working hard behind the scenes to be ready for the chance and I'm really pleased with the way I contributed.
"We have a strong side and depth here so it is really hard to get into the team. I've been working hard to get in and it was nice to get out there today."
The bonus-point victory put Vipers in command of third place after their defeat of The Blaze, while Thunder remain fourth.
Thunder chose to bat first with both sides shorn of their England contract players, with Lauren Bell, Wyatt, Charlie Dean, Bouchier, Kate Cross, Sophie Ecclestone, and Emma Lamb all called up for red-ball training ahead of the Ashes Test.
Thunder's batters collectively struggled to make the most of starts, with Liberty Heap, Deandra Dottin, Ellie Threlkeld and Danni Collins all scoring between 15 and 24 but none could turn them into innings-defining scores.
They were throttled by accurate bowling from the experienced Vipers bowlers Anya Shrubsole, Smith, Adams and, on her birthday, Georgia Elwiss - none of which went for more than 6.25 runs per over.
But Thunder self-sabotaged with four run-outs of varying degrees of barbecuing and mix-ups, which accounted for the wickets of Fi Morris, Seren Smale, Steph Butler and Olivia Bell.
A used pitch made flowing shot-making difficult although they totted up 47 for 2 in the powerplay, aided by Heap's quartet of boundaries. West Indian Dottin showed some flair with a vicious cut and flail over cover combo off Mary Taylor before slog-sweeping Adams for six.
But the belt tightened, Elwiss went for 14 off her for overs while Shrubsole, Smith and Adams picked up two wickets each as the last seven wickets fell for just 30 runs.
In reply, Vipers' new-look opening pair of Nicole Faltum and McCaughan effortlessly put on 33 together before the Australian cut to point and Taylor joined the run out party.
Left-arm all-rounder Naomi Dattani had pilfered the first wicket, and the first two overs with impeccable figures of 2-2-0-1.
But Adams and McCaughan took control. Adams started slowly with 15 coming from her first 17 balls before tearing into former team-mate Tara Norris with three successive fours before bring up the fifty stand by carting Bell into the stands.
She departed two balls later attempting another big shot before Freya Kemp and McCaughan were bowled by Bell.
Nancy Harman became the sixth run out victim but Elwiss whacked a six back over Bell's head to win it with 23 balls to spare.