The conditional pick is a seventh-round selection in 2018 and will be based on Inman's production this season, sources told ESPN's Adam Schefter.
Inman, 28, has appeared in just four games this season with two receptions for 9 yards. But he had a career-best season in 2016 when he started all 16 games and caught 58 passes for 810 yards and 4 touchdowns.
He has been inactive for the Chargers' past two games but was a healthy scratch for the Chargers' Week 7 game against the Denver Broncos.
"He got hurt and never really got a good chance to see him, and some other guys stepped ahead of him,'' Lynn told reporters, according to the The Associated Press. "We just wanted to get him someplace where he can be happy and play football.''
Rookie wide receiver Mike Williams, the No. 7 overall pick in the 2017 draft, has been active the past two weeks and now will get more put on his plate, Lynn said.
"I'm going to feed him more than he can eat right now," Lynn said, according to the AP.
The Bears, who lost top receiver Cameron Meredith for the season in August and placed Kevin White on injured reserve in September, are in need of help at wide receiver as, other than Kendall Wright, the team's production at the position has been slim.
Markus Wheaton also has been slowed by a groin injury.
Wright, who signed with the Bears last offseason, has 20 receptions and is tied with tight end Zach Miller for the team lead with 236 receiving yards.
Rookie running back Tarik Cohen leads the team in receptions with 27.
"He's a veteran guy," Fox told reporters, according to the Chicago Sun-Times. "We have a young room. So anxious to see how that goes."
Quarterback Mitchell Trubisky said he's looking forward to Inman's arrival.
"Hear he's a good player. I'll just help him any way I can. He's part of this team and family now. We're invested in all our guys. We're going to get him as ready as we can, as well as the other guys," he told reporters, according to CBS Chicago.